This application claims the benefit of Korean Patent Application No. 2000-58741, filed on Oct. 6, 2000, under 35 U.S.C. xc2xa7 119, the entirety of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an organic [EL] electroluminescent (or EL) device, and, more particularly, to an organic electroluminescent device having a multilayer printed circuit board.
2. Description of Related Art
FIG. 1 is a cross sectional view illustrating a configuration of a conventional organic EL device 5. As shown in FIG. 1, the conventional EL device 5 includes a first electrode or anode electrode 11 formed on a substrate 10, and a second electrode or cathode electrode 17 with an EL light-emitting layer 12 interposed therebetween. Preferably, the anode electrode 11 is made of a transparent material such as indium tin oxide (ITO), and the cathode electrode 17 is made of Al, Mg, Ag, Ca, or Ba, or the like.
The EL light-emitting layer 12 includes a hole transport layer, a luminescent layer, and an electron transport layer. A metal layer 15 is formed to protect the EL light-emitting layer 12 from humidity, oxygen, and an external impact. The metal layer 15 is fixed to the anode electrode 11 by an adhesive 16. The metal layer 15 has a hygroscopic agent 14 in the form of a powder in space formed by a filter 13. The filter 13 merely serves to prevent the hygroscopic agent 14 from leaking out the space formed by the filter 13 and the metal layer 15. Therefore, when the hygroscopic agent 14 is attached to an inner surface of the metal layer 15 by a predetermined method, the filter 13 may be removed.
However, in the conventional EL device 5 having such a configuration, since a printed circuit board having components to drive the EL device 5 should be separately disposed, a problem arise in that the volume or size of the device 5 increases, leading to an undesirable appearance. More particularly, because of the above-mentioned problem with the conventional device 5, it is difficult to obtain a compact organic EL device.
In efforts to protect the organic EL light-emitting layer 12 from humidity or oxygen, a multi-layered structure in which a metal layer and a resin layer are repeatedly coated is suggested. However, the organic EL device of such a structure has further problems in that processing time is long and production cost is high.
To overcome the problems described above, preferred embodiments of the present invention provide a compact organic EL electroluminescent (or EL) device.
It is another object of the present invention to provide a compact El device.
It is another abject of the present invention is to provide an organic EL device having a short processing time.
It is also another abject of the present invention is to provide an organic EL device having a low production cost.
In order to achieve the above-mentioned objects, the present invention comprises an organic EL device comprising a first electrode, a second electrode, an EL light-emitting layer, and a printed circuit board. In the EL device of the present invention, the first electrode is formed on a transparent substrate. The second electrode is spaced apart from the first electrode and together with the first electrode applies an electric current to the organic EL device. The EL light-emitting layer is interposed between the first and second electrodes. The printed circuit board or a flexible printed circuit board include a multi-layered structure and is attached to the first electrode to cover the EL light-emitting layer.
The organic EL device of the present invention further includes a hygroscopic agent attached to a bottom surface of the printed circuit board or the flexible printed circuit board. The printed circuit board or the flexible printed circuit board includes metal layers and a resin layer. The metal included in the metal layers is a low resistance metal such as Cu, Ag, Au, or Ni or their alloy. The metal layers of the printed circuit board or the flexible printed circuit board are connected with the first and second electrodes via an anithotropic conductive film (ACF). The printed circuit board or the flexible printed circuit board includes a drive intergrated circuit (IC). The drive IC is connected with the first and second electrodes via one of a chip on board (COB), a tape automated bonding (TAB), and a chip on glass (COG). The printed circuit board or the flexible printed circuit board is attached to the first electrode via an adhesive.
The organic EL device according to the preferred embodiment of the present invention has the following advantages. Firstly, since the printed circuit board or the flexible printed circuit board of the multi-layered structure serves to protect the EL light-emitting layer from humidity, oxygen, external impact, and the like, a compact organic EL device can be obtained. Secondly, instead of using the metal layer according to the conventional art, the printed circuit board or the flexible printed circuit board having a multi-layered structure which is in common use is used, and, thus, the manufacturing process is simple, and the processing time is short. Thirdly, a production cost is low.